chore: Add type for metric units

[sentrivana]

SDKs should not restrict what strings can be sent as a metric unit, but should provide hints/types/constants to help determine what values are supported.

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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New Features ✨

• feat(ai): add parse_data_uri function to parse a data URI by constantinius in #5311
• feat(asyncio): Add on-demand way to enable AsyncioIntegration by sentrivana in #5288

Bug Fixes 🐛

• fix(ai): redact message parts content of type blob by constantinius in #5243
• fix(clickhouse): Guard against module shadowing by alexander-alderman-webb in #5250
• fix(gql): Revert signature change of patched gql.Client.execute by alexander-alderman-webb in #5289
• fix(grpc): Derive interception state from channel fields by alexander-alderman-webb in #5302
• fix(litellm): Guard against module shadowing by alexander-alderman-webb in #5249
• fix(pure-eval): Guard against module shadowing by alexander-alderman-webb in #5252
• fix(ray): Guard against module shadowing by alexander-alderman-webb in #5254
• fix(threading): Handle channels shadowing by sentrivana in #5299
• fix(typer): Guard against module shadowing by alexander-alderman-webb in #5253
• fix: Send client reports for span recorder overflow by sentrivana in #5310

Documentation 📚

• docs(metrics): Remove experimental notice by alexander-alderman-webb in #5304
• docs: Update Python versions banner in README by sentrivana in #5287

Internal Changes 🔧

Release

• ci(release): Bump Craft version to fix issues by BYK in #5305
• ci(release): Switch from action-prepare-release to Craft by BYK in #5290

Other

• chore(gen_ai): add auto-enablement for google genai by shellmayr in #5295

• chore: Add type for metric units by sentrivana in #5312

• ci: Update tox and handle generic classifiers by sentrivana in #5306

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[alexander-alderman-webb]

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